Custom Stock Tracking by variants

We have a custom, MVC implementation of Kentico that integrates with an ERP system for the product management.
Currently, we have all products set to track stock by variants, this allows us to link the variants to the ERP variants, and have stock per variant, but we'd like to stop Kentico's in-built functionality to reduce the stock count on a sale, and replace it with our own syncing with the ERP.